Luminance enhancement film and backlight unit including the same

Abstract

Disclosed is a luminance enhancement film which is suitable for use in a display and includes a multilayered thin film and a uniaxially drawn film formed on one surface of the multilayered thin film.

The invention claimed is: 
     
       1. A luminance enhancement film, comprising:
 a multilayered thin film including a plurality of first thin films which are optically isotropic and a plurality of second thin films which are optically anisotropic, and having a reflective axis which reflects incident light and a transmissive axis which transmits the light; 
 a uniaxially drawn film disposed on at least one surface of the multilayered thin film; and 
 an adhesive layer disposed between the uniaxially drawn film and the multilayered thin film. 
 
     
     
       2. The luminance enhancement film of  claim 1 , further comprising an anti-blocking layer which is disposed on other surface of the multilayered thin film where no uniaxially drawn film is disposed. 
     
     
       3. The luminance enhancement film of  claim 2 , wherein a haze of the anti-blocking layer is 1-30%. 
     
     
       4. The luminance enhancement film of  claim 1 , further comprising a light diffusion layer formed on the uniaxially drawn film. 
     
     
       5. The luminance enhancement film of  claim 4 , wherein the light diffusion layer comprises a binder resin; and 20-200 parts by weight of light diffusing particles based on 100 parts by weight of the binder resin. 
     
     
       6. The luminance enhancement film of  claim 5 , wherein the light diffusing particles include at least one type of particles selected from the group consisting of first light diffusing particles having an average particle size of 1-20 μm and second light diffusing particles having an average particle size of 20-40 μm. 
     
     
       7. The luminance enhancement film of  claim 6 , wherein the light diffusing particles include the first light diffusing particles and the second light diffusing particles at a mixing ratio of 10:90-90:10. 
     
     
       8. The luminance enhancement film of  claim 5 , wherein the light diffusing particles include first light diffusing particles having an average particle size of 1-20 μm and a refractive index of n 1  and second light diffusing particles having an average particle size of 20-40 μm and a refractive index of n 2 , with a condition that |n 1 −n 2 |>0.02. 
     
     
       9. The luminance enhancement film of  claim 4 , wherein a thickness of the light diffusion layer is 0.05-0.5 times a thickness of the multilayered thin film. 
     
     
       10. The luminance enhancement film of  claim 4 , wherein a haze of the light diffusion layer is 30-100%. 
     
     
       11. The luminance enhancement film of  claim 1 , wherein the uniaxially drawn film is selected from the group consisting of a polyethyleneterephthalate film, a polycarbonate film, a polyethylene film, a polystyrene film and a polyepoxy film. 
     
     
       12. The luminance enhancement film of  claim 1 , wherein an in-plane refractive index difference (Δn=|nx−ny|) of the uniaxially drawn film is 0.03 or more, in which nx is a refractive index in a drawing direction of the uniaxially drawn film and ny is a refractive index in a direction perpendicular to the drawing direction. 
     
     
       13. The luminance enhancement film of  claim 1 , wherein a refractive index of the uniaxially drawn film is 1.0-1.65. 
     
     
       14. The luminance enhancement film of  claim 1 , wherein an angle formed by the optical axis of the uniaxially drawn film and the reflective axis of the multilayered thin film is 40° or less. 
     
     
       15. The luminance enhancement film of  claim 1 , wherein an angle formed by the optical axis of the uniaxially drawn film and the reflective axis of the multilayered thin film is 0°. 
     
     
       16. The luminance enhancement film of  claim 1 , wherein a drawing direction of the uniaxially drawn film is a machine direction. 
     
     
       17. The luminance enhancement film of  claim 1 , wherein a drawing direction of the uniaxially drawn film is a transverse direction. 
     
     
       18. A backlight unit including the luminance enhancement film of  claim 1 . 
     
     
       19. The luminance enhancement film of  claim 1 , wherein a surface contact angle of the multilayered thin film is 50-85°. 
     
     
       20. The luminance enhancement film of  claim 1 , wherein a resin for the first thin films or the second thin films of the multilayered thin film includes a polymer resin which is not subjected to solid polymerization.